Merge pull request #1046 from onyn/feat/service-config

feat: apply grpc service config from consul (#1045)

docs/en/client/configuration.md

@@ -69,7 +69,7 @@ There are a number of supported schemes, that you can use to determine the targe
 - `discovery` (Prio 6): \
   (Optional) Uses spring-cloud's `DiscoveryClient` to lookup appropriate targets. The connections will be refreshed
   automatically during `HeartbeatEvent`s. Uses the `gRPC_port` metadata to determine the port, otherwise uses the
-  service port. \
+  service port. Uses the `gRPC_service_config` metadata to determine [service config](https://grpc.github.io/grpc/core/md_doc_service_config.html). \
   Example: `discovery:///service-name`
 - `self` (Prio 0): \
   The self address or scheme is a keyword that is available, if you also use `grpc-server-spring-boot-starter` and

grpc-client-spring-boot-starter/src/main/java/net/devh/boot/grpc/client/nameresolver/DiscoveryClientNameResolver.java

@@ -22,6 +22,7 @@
 import static net.devh.boot.grpc.client.nameresolver.DiscoveryClientResolverFactory.DISCOVERY_INSTANCE_ID_KEY;
 import static net.devh.boot.grpc.client.nameresolver.DiscoveryClientResolverFactory.DISCOVERY_SERVICE_NAME_KEY;
 import static net.devh.boot.grpc.common.util.GrpcUtils.CLOUD_DISCOVERY_METADATA_PORT;
+import static net.devh.boot.grpc.common.util.GrpcUtils.CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG;
 
 import java.net.InetSocketAddress;
 import java.util.List;
@@ -35,6 +36,8 @@
 import org.springframework.util.CollectionUtils;
 
 import com.google.common.collect.Lists;
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
 
 import io.grpc.Attributes;
 import io.grpc.Attributes.Builder;
@@ -58,13 +61,15 @@ public class DiscoveryClientNameResolver extends NameResolver {
     @Deprecated
     private static final String LEGACY_CLOUD_DISCOVERY_METADATA_PORT = "gRPC.port";
     private static final List<ServiceInstance> KEEP_PREVIOUS = null;
+    private static final Gson GSON = new Gson();
 
     private final String name;
     private final DiscoveryClient client;
     private final SynchronizationContext syncContext;
     private final Consumer<DiscoveryClientNameResolver> shutdownHook;
     private final SharedResourceHolder.Resource<Executor> executorResource;
     private final boolean usingExecutorResource;
+    private final ServiceConfigParser serviceConfigParser;
 
     // The field must be accessed from syncContext, although the methods on an Listener2 can be called
     // from any thread.
@@ -93,6 +98,7 @@ public DiscoveryClientNameResolver(final String name, final DiscoveryClient clie
         this.executor = args.getOffloadExecutor();
         this.usingExecutorResource = this.executor == null;
         this.executorResource = executorResource;
+        this.serviceConfigParser = args.getServiceConfigParser();
     }
 
     /**
@@ -187,6 +193,55 @@ protected int getGrpcPort(final ServiceInstance instance) {
         }
     }
 
+    /**
+     * Extracts and parse gRPC service config from the given service instances.
+     *
+     * @param instances The list of instances to extract the service config from.
+     * @return Parsed gRPC service config or null.
+     */
+    private ConfigOrError resolveServiceConfig(List<ServiceInstance> instances) {
+        final String serviceConfig = getServiceConfig(instances);
+        if (serviceConfig == null) {
+            return null;
+        }
+        log.debug("Found service config for {}", getName());
+        if (log.isTraceEnabled()) {
+            // This is to avoid blowing log into several lines if newlines present in service config string.
+            final String logStr = serviceConfig.replace("\r", "\\r").replace("\n", "\\n");
+            log.trace("Service config for {}: {}", getName(), logStr);
+        }
+        try {
+            @SuppressWarnings("unchecked")
+            Map<String, ?> parsedServiceConfig = GSON.fromJson(serviceConfig, Map.class);
+            return serviceConfigParser.parseServiceConfig(parsedServiceConfig);
+        } catch (JsonSyntaxException e) {
+            return ConfigOrError.fromError(
+                    Status.UNKNOWN
+                            .withDescription("Failed to parse grpc service config")
+                            .withCause(e));
+        }
+    }
+
+    /**
+     * Extracts the gRPC service config string from the given service instances.
+     *
+     * @param instances The list of instances to extract the service config from.
+     * @return The gRPC service config or null.
+     */
+    protected String getServiceConfig(final List<ServiceInstance> instances) {
+        for (final ServiceInstance inst : instances) {
+            final Map<String, String> metadata = inst.getMetadata();
+            if (metadata == null || metadata.isEmpty()) {
+                continue;
+            }
+            final String metaValue = metadata.get(CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG);
+            if (metaValue != null && !metaValue.isEmpty()) {
+                return metaValue;
+            }
+        }
+        return null;
+    }
+
     /**
      * Gets the attributes from the service instance for later use in a load balancer. Can be overwritten to convert
      * custom attributes.
@@ -318,6 +373,7 @@ private List<ServiceInstance> resolveInternal() {
             log.debug("Ready to update server list for {}", getName());
             this.savedListener.onResult(ResolutionResult.newBuilder()
                     .setAddresses(toTargets(newInstanceList))
+                    .setServiceConfig(resolveServiceConfig(newInstanceList))
                     .build());
             log.info("Done updating server list for {}", getName());
             return newInstanceList;

grpc-client-spring-boot-starter/src/test/java/net/devh/boot/grpc/client/nameresolver/DiscoveryClientNameResolverTest.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2016-2023 The gRPC-Spring Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.devh.boot.grpc.client.nameresolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.net.InetSocketAddress;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.cloud.client.DefaultServiceInstance;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClient;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryProperties;
+
+import io.grpc.NameResolver;
+import io.grpc.Status;
+import io.grpc.SynchronizationContext;
+import io.grpc.internal.AutoConfiguredLoadBalancerFactory;
+import io.grpc.internal.GrpcUtil;
+import io.grpc.internal.ScParser;
+import net.devh.boot.grpc.common.util.GrpcUtils;
+
+/**
+ * Test for {@link DiscoveryClientNameResolver}.
+ */
+public class DiscoveryClientNameResolverTest {
+
+    private final NameResolver.Args args = NameResolver.Args.newBuilder()
+            .setDefaultPort(1212)
+            .setProxyDetector(GrpcUtil.DEFAULT_PROXY_DETECTOR)
+            .setSynchronizationContext(
+                    new SynchronizationContext((t, e) -> {
+                        throw new AssertionError(e);
+                    }))
+            .setServiceConfigParser(new ScParser(true, 10, 10, new AutoConfiguredLoadBalancerFactory("pick_first")))
+            .setOffloadExecutor(Runnable::run)
+            .build();
+
+    @Test
+    void testValidServiceConfig() {
+        String validServiceConfig = """
+                {
+                  "loadBalancingConfig": [
+                    {"round_robin": {}}
+                  ],
+                  "methodConfig": [
+                    {
+                      "name": [{}],
+                      "retryPolicy": {
+                        "maxAttempts": 5,
+                        "initialBackoff": "0.05s",
+                        "maxBackoff": "1s",
+                        "backoffMultiplier": 2,
+                        "retryableStatusCodes": [
+                          "UNAVAILABLE",
+                          "ABORTED",
+                          "DATA_LOSS",
+                          "INTERNAL",
+                          "DEADLINE_EXCEEDED"
+                        ]
+                      },
+                      "timeout": "5s"
+                    }
+                  ]
+                }
+                """;
+        TestableListener listener = resolveServiceAndVerify("test1", validServiceConfig);
+        NameResolver.ConfigOrError serviceConf = listener.getResult().getServiceConfig();
+        assertThat(serviceConf).isNotNull();
+        assertThat(serviceConf.getConfig()).isNotNull();
+        assertThat(serviceConf.getError()).isNull();
+    }
+
+    @Test
+    void testBrokenServiceConfig() {
+        TestableListener listener = resolveServiceAndVerify("test2", "intentionally invalid service config");
+        NameResolver.ConfigOrError serviceConf = listener.getResult().getServiceConfig();
+        assertThat(serviceConf).isNotNull();
+        assertThat(serviceConf.getConfig()).isNull();
+        assertThat(serviceConf.getError()).extracting(Status::getCode).isEqualTo(Status.Code.UNKNOWN);
+    }
+
+    private TestableListener resolveServiceAndVerify(String serviceName, String serviceConfig) {
+        SimpleDiscoveryProperties props = new SimpleDiscoveryProperties();
+        DefaultServiceInstance service = new DefaultServiceInstance(
+                serviceName + "-1", serviceName, "127.0.0.1", 3322, false);
+        Map<String, String> meta = service.getMetadata();
+        meta.put(GrpcUtils.CLOUD_DISCOVERY_METADATA_PORT, "6688");
+        meta.put(GrpcUtils.CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG, serviceConfig);
+        props.setInstances(Map.of(serviceName, List.of(service)));
+        SimpleDiscoveryClient disco = new SimpleDiscoveryClient(props);
+        DiscoveryClientNameResolver dcnr = new DiscoveryClientNameResolver(serviceName, disco, args, null, null);
+
+        TestableListener listener = new TestableListener();
+        dcnr.start(listener);
+
+        assertThat(listener.isErrorWasSet()).isFalse();
+        assertThat(listener.isResultWasSet()).isTrue();
+        InetSocketAddress addr = (InetSocketAddress) listener.getResult().getAddresses().get(0).getAddresses().get(0);
+        assertThat(addr.getPort()).isEqualTo(6688);
+        assertThat(addr.getHostString()).isEqualTo("127.0.0.1");
+        return listener;
+    }
+}

grpc-client-spring-boot-starter/src/test/java/net/devh/boot/grpc/client/nameresolver/TestableListener.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2016-2023 The gRPC-Spring Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.devh.boot.grpc.client.nameresolver;
+
+import io.grpc.NameResolver;
+import io.grpc.Status;
+import lombok.Getter;
+
+@Getter
+public class TestableListener extends NameResolver.Listener2 {
+
+    private NameResolver.ResolutionResult result;
+    private Status error;
+    private boolean resultWasSet = false;
+    private boolean errorWasSet = false;
+
+    @Override
+    public void onResult(NameResolver.ResolutionResult resolutionResult) {
+        this.result = resolutionResult;
+        resultWasSet = true;
+    }
+
+    @Override
+    public void onError(Status error) {
+        this.error = error;
+        errorWasSet = true;
+    }
+
+}

grpc-common-spring-boot/src/main/java/net/devh/boot/grpc/common/util/GrpcUtils.java

@@ -40,6 +40,11 @@ public final class GrpcUtils {
      */
     public static final String CLOUD_DISCOVERY_METADATA_PORT = "gRPC_port";
 
+    /**
+     * The cloud discovery metadata key used to identify service config.
+     */
+    public static final String CLOUD_DISCOVERY_METADATA_SERVICE_CONFIG = "gRPC_service_config";
+
     /**
      * The constant for the grpc server port, -1 represents don't start an inter process server.
      */